I’m continuing down the road of adding Deploy to Heroku support to various apps, and using my site as a test case for IndieWeb stuff. I went down the rabbit hole today because infominer was looking at the Jekyll IndieWeb template, and I found @voxpelli’s WebMention’s server at voxpelli/webpage-webmentions.
I forked it bmann/webpage-webmentions and got Deploy to Heroku working by just adding an app.json.